Wheel treads are designed to adhere to the running surface (top) of the rails of a railway track essentially by means of friction. It is this friction between the treads and the top of the rails that allows the wheels to gain traction on the rails as the wheels rotate and thereby propel the train along the tracks. A wheel flange is that tapered projection that extends completely around the inner portion of the rim of a wheel. The wheel flanges are designed to keep the wheels or wheelsets on the railway track by limiting lateral movement of the wheels or wheelsets against the inside surface of either rail.
Due to their contact with the railway track, the wheels of a locomotive suffer wear over time, particularly on their treads and to a lesser extent on their flanges. The treads, of course wear as a result of their direct contact against the top of the rail. During braking the treads may suffer wear more severely if the wheels should happen to slip or lockup as they slide along the rail. The wheel flanges suffer wear due to their contact with the inside surfaces of the rails. This is particularly pronounced as the trains negotiate curves in a railway track. On such curves the flange portion of the wheel makes very firm contact with inside surface of the rails.
Wheel lubrication systems are one of the many systems that the railroad industry uses to prolong the useful life of a railroad wheel. Such wheel lubrication systems are used to lubricate the flange of the wheels of a railroad locomotive. These flange lubrication systems include both wayside lubricators and on-board lubricators.
In these systems nozzles have, through the years, proven to be the least reliable component of the wheel flange lubrication system. Some prior art nozzles have employed a steel ball as a check valve internally to prevent or permit the delivery of a dose of lubricant. When the spray solenoid is deenergized, the ball valve is biased to a closed position in which the pressurized lubricant is blocked from exiting the nozzle. When the solenoid is energized the force of air moves the ball valve to an open position and allows the lubricant to flow out of the nozzle and onto the wheel flange.
These prior art nozzles have not fared well in the railroad environment where they are intended to be used. Dirt, dust and other debris can work their way into the nozzle and after a while impede the movement of the internal ball valve. In many of these instances the ball valve would tend to stick in a closed position regardless of the state of the solenoid. When this occurs lubricant is not expelled from the nozzle because the grease path is blocked by the ball valve.